It is known to provide an overhead projector which has a swingable arm on the base or housing of the projector in which the pivot is exposed at the side of the apparatus above the top of the housing. This pivot, therefore, is always visible. In addition, the pivot must be provided with a locking device actuated by the operator before it permits pivoting of the arm into its horizontal position to collapse the overhead projectors. This lock mechanism is also exposed at the pivot.
Pivots which are exposed pose attractive nuisances for children, create locations which can pose a danger to the user, especially for an inexperienced user, and frequently prevent use of the apparatus in a school or other environment at which the device may be handled by inexperienced operators or juveniles.
Furthermore, the locking mechanism contributes to the cost of the overhead projector and ma make the cost prohibited.